In order to detect the molecular mechanisms whereby human immunodeficiency virus (HIV-1) functionally alters or kills CD4+ T lymphocytes Jurkat cell lines transfected to express different HIV-1 proteins were established. Cells constitutively expressing functional gp120 and gp41 showed no direct alterations in their cell growth but did not spontaneously fuse. In contrast, HIV-infected cells or HIV-envelope transfected cells could be induced to from syncytium and die upon co-culture with naive cells. Such infected or transfected cells undergoing cell fusion and cell death displayed dramatic alterations in their intracellular signalling pathways as evaluated by changes in tyrosine phosphorylation of intracellular substrates. These phosphorylations include the induction of tyrosine phosphate on substrates of 95 and 30 kilodaltons (kd), the latter event displaying kinetic correlation with syncytium formation and cell death. Constructs for the inducible or constitutive T cell expression of HIV-1 nef, vpu, rev, and tat were prepared to permit the functional evaluation of each of these HIV-1 genes both in vitro and in the scid/hu mouse model. Peripheral blood CD4+ T lymphocytes infected in vitro with HIV-1 were found to give rise to CD4-/CD8- gamma/delta (gamma/delta T lymphcytes that did not express interleukin-2 (IL-2) following stimulation. In studies on the peripheral blood mononuclear cells of patients with HIV infection an increased proportion of cells expressing gamma/delta T cell receptor were identified. The heavy and light chain antibody genes derived from two human anti-HIV envelope gp41 monoclonal cell lines were cloned, sequenced, and functionally expressed in recipient B cell lines. The genes from one of the two monoclonal lines conferred anti-gp4l specificity to transfected cell lines. The heavy and light chain variable region genes from this antibody (98-6) were genetically linked to the T cell receptor (TCR) constant alpha and beta regions, respectively to generate chimeric antibody/TCR genes capable of expression in T lymphocytes.